arithmetic module
pep8
Merge branch 'root-repo'
handle long reply message
solve timout calculation
add unittest
more arithmetic matching pattern
add timeout utility script
pep8
change backend to sympy; dependency update; case update
Allow advanced operators

   * Matching expression allow 'a-z', 'A-Z' and ','
   * Case fixed according to new matching
remove old comments
conversion between '^' and '**'
Merge pull request #26 from hupili/master

计算鸡 plugin